WS-C6509-E and per VRF BGP route-id (IPv6)

Basically how (and if) is it possible to define a BGP router-id under family ipv6 VRF?

At first I thought the family ipv6 vrf bgp would use the lowest loopback/ip from its own vrf (ipv4 family).

But apparently it's using the router-id from global?

Also it doesn't seem to be possible to configure router-id under family ipv6.

VSS1(config-router)#address-family ipv4 vrf VPNA VSS1(config-router-af)#bgp ?   aggregate-timer        Configure Aggregation Timer   dampening              Enable route-flap dampening   redistribute-internal  Allow redistribution of iBGP into IGPs (dangerous)   router-id              Router identifier configuration   suppress-inactive      Suppress routes that are not in the routing table VSS1(config-router-af)#exit VSS1(config-router)#address-family ipv6 vrf VPNB VSS1(config-router-af)#bgp ?   aggregate-timer        Configure Aggregation Timer   dampening              Enable route-flap dampening   redistribute-internal  Allow redistribution of iBGP into IGPs (dangerous) 

12.2(17r)SX7 in question.